"I've got to tell you, my acting improved when I was unmasked," laughs Paxton to
Zap2it when talking about his character John Garrett. "Playing the nice, square guy was OK, but god, once they unmasked me I felt like I was unchained, uncensored. So I had a ball with it. I had a good time."

"Tonight's a great episode because they got to tell some of the backstory," he says. "It is revealing insomuch as you learn kind of a little more what makes [Garrett] tick and why he went over to the other side."

The majority of Paxton's scenes have been opposite Dalton, and he says he's seen his onscreen protege blossom in his HYDRA role just like he did.

"Brett has grown a lot. I really am a fan of his," Paxton says. "What's interesting about tonight's episode is you see [Ward's] earlier years. They have a younger actor playing him, [who] does a great job, and you see how he became kind of beholden to me in kind of a weird surrogate father-son relationship."

Paxton wouldn't reveal any details about the "Agents of SHIELD" season finale, but he promised some changes to come. "I think, yes, you're going to find some more twists and turns," he says. "They've set it up for next year too."

"Marvel's Agents of SHIELD" airs Tuesdays at 8 p.m. ET/PT on ABC. Only two episodes remain of Season 1.